When was the first fossil lamprey with a modern body structure reported?

The first fossil lamprey with a modern body structure was reported in 1968. This specimen was discovered in Middle Pennsylvanian deposits in Illinois, which are more than 300 million years old. Prior to this discovery, cyclostomes—the group that includes modern lampreys and hagfishes—were unknown in the fossil record because they lack the hard, mineralized body parts that are typically preserved as fossils.1